The present invention relates to capsule assemblies for mixing two or more materials, and particularly of the self-actuating type of capsule assemblies in which the materials to be mixed are normally separated but are brought together automatically upon vibrating the assembly. Such mixing capsule assemblies are commonly used in preparing dental amalgams. The invention is therefore described below with respect to this application, but it will be appreciated that the invention could advantageously be used in many other situations as well.
Many diverse types of mixing capsules have been designed particularly for use in producing dental amalgams by mixing mercury with a powder. Among the known types of mixing capsules are those which include two compartments separated by a friction-fitted barrier which is removed upon mixing, or by a web which is ruptured upon mixing. Another known type includes an outer capsule containing one material, and an inner capsule containing the other, e.g. mercury, which inner capsule is in the form of a sealed aluminum foil or plastic bag which is ruptured upon mixing. In another known type, the inner capsule is in the form of a container having a fine outlet opening and a ball frictionally received within the container so as to cover and uncover the opening during the vibration of the capsule. The foregoing known types of mixing capsules, however, are not entirely satisfactory from all the standpoints of assuring complete separation of the two materials until mixing is to be effected, and promoting the thorough mixing of the two materials when the capsule is vibrated, while still retaining a simple inexpensive construction susceptible to volume production at low cost.
An object of the present invention is to provide a novel mixing capsule assembly having advantages in the above respects.